During the Civil War, Revels, a college-educated minister, helped form African American army regiments for the Union cause, started a school for freed men, and served as a chaplain for the Union army. Posted to Mississippi, Revels remained in the former Confederate state after the war and entered into Reconstruction-era Southern politics.
In 1867, the first Reconstruction Act was passed by Congress, dividing the South into five military districts and granting suffrage to all male citizens, regardless of race. A politically mobilized African American community joined with white allies in the Southern states to elect the Republican party to power, which in turn brought about radical changes across the South. By 1870, all the former Confederate states had been readmitted to the Union, and most were controlled by the Republican Party, thanks in large part to the support of African American voters.
On January 20, 1870, Hiram R. Revels was elected by the Mississippi legislature to fill the Senate seat once held by Jefferson Davis, the former president of the Confederacy. On February 25, two days after Mississippi was granted representation in Congress for the first time since it seceded in 1861, Revels was sworn in.
Although African Americans Republicans never obtained political office in proportion to their overwhelming electoral majority, Revels and some 15 other African American men served in Congress during Reconstruction, more than 600 served in state legislatures, and hundreds of African Americans held local offices.